In liquid crystal display devices such as liquid crystal television devices, liquid crystal panels that are display panels do not emit light. Therefore, liquid crystal display devices require backlight devices as external lighting devices. The backlight devices are classified broadly into a direct type and an edge-light type based on mechanisms. For further reduction in thicknesses of the liquid crystal display devices, the edge-light type backlight devices are more preferable.
In the edge-light type backlight device, a light guide plate may thermally expand and the expansion of the light guide plate may change the distance between a light source, such as LEDs, and the light guide plate and this may degrade light use efficiency of light emitted by the light sources. It has been known that fixing members that fix a board including the light source thereon to the light guide plate are provided to maintain such a distance between the light source and the light guide plate constant and thus an optical design is maintained preferable. A lighting device including such a configuration is disclosed in Patent Document 1. In the lighting device, a printed circuit board including LEDs thereon includes positioning bosses that are fitted in holes of a light guide plate. According to this configuration, the distance between the LEDs and the light guide plate may be maintained constant.